1. Field of the Invention
An aspect of the present invention relates to an image forming apparatus and more particularly, to an image forming apparatus having a safety sensor.
2. Description of the Related Art
Generally, an image forming apparatus, such as a copier or a laser printer, performs printing by producing an image using a laser beam and fixing the image onto a printing medium.
In FIG. 1, a conventional image forming apparatus 1 comprises a main body 10, a paper feeding unit 20, a laser scan unit 30, a developing unit 40, a transfer roller 50, a fixing unit 60, and a discharge unit 70.
The main body 10 supports arrangement and operation of the other component parts such as the paper feeding unit 20, the laser scan unit 30, the developing unit 40, the transfer roller 50, the fixing unit 60, and the discharge unit 70.
The paper feeding unit 20 stores predetermined sheets of a printing medium and supplies the printing medium sheet by sheet. The paper feeding unit 20 comprises a paper supply cassette 21 and a pickup roller 22. The laser scan unit 30 projects a laser beam according to printing data onto a photoconductive drum 41, thereby generating an electrostatic latent image. The developing unit 40 comprises the photoconductive drum 41 on which the electrostatic latent image is generated, a developing roller 42 developing the electrostatic latent image by supplying toner, and a toner hopper 43 storing a predetermined amount of the toner. The transfer roller 50 rotates in contact with the photoconductive drum 41 to transfer the image formed on the photoconductive drum 41 to the printing medium. The fixing unit 60 fixes the image as transferred to the printing medium by heat and pressure. The fixing unit 60 comprises a pressing roller 61 and a heating roller 62. The discharge unit 70 includes a discharging roller 71 to eject the printing medium on which image fixation is completed toward a discharge tray 73 formed outside of the main body 10.
As described above, the image forming apparatus 1 forms the electrostatic latent image on the photoconductive drum 41 by projecting the laser beam from the laser scan unit 30 and fixes the image by applying heat and pressure through the fixing unit 60. Herein, however, direct exposure to the laser beam and the heat and pressure may be harmful for a user. Therefore, the image forming apparatus 1 is required to prevent access of the user to a laser beam path or to the fixing unit. Conventionally, for this purpose, an entrance and a moving path of the printing medium is so narrowly formed that the user cannot access them, or mechanical protectors are mounted to all the operational paths where the user may access.
However, when the entrance and the moving path for the printing medium are too narrow, accessibility of the user is deteriorated in the case that the image forming apparatus 1 encounters trouble. For example, when a paper jam is generated, it is difficult for the user to remove the jammed printing medium.
Furthermore, when the mechanical protectors are provided to all the necessary parts, the manufacturing cost increases and compactness of the image forming apparatus 1 is lost.